1. Field of the Invention
The present invention relates to an electronic component chip feeder for feeding electronic component chips to a case substrate or a printed circuit board to be placed with electronic components, and more specifically, it relates to an electronic component chip feeder equipped with a system for cleaning the surfaces of electrodes formed on the outer surfaces of electronic component chips.
The present invention also relates to a manufacturing method of electronic devices by feeding electronic component chips to a case substrate or by feeding electronic components as finished products to a printed board, etc., and more specifically, it relates to a manufacturing method of electronic devices including a cleaning step of the outer surfaces of electronic components in manufacturing steps thereof.
In addition, in this specification, the term “electronic component chip” signifies not only a part or a component of an electronic component as a finished product but also an electronic component as a finished product. In the present invention, the term “electronic device” also signifies not only the one generally called “electronic component” but also a combination of such electronic components having a specified function.
2. Description of the Related Art
Hitherto, an electronic component chip feeder has been used for mounting electronic component chips on a printed circuit board or for mounting elements forming electronic component chips on a case substrate.
Referring to FIG. 7, a conventional electronic component feeder will be generally described.
An electronic component feeder 51 comprises a hopper 52, a buffer portion 53, and a chute portion 54. The hopper 52 has a volume capable of accommodating numerous electronic component chips with a supplying inlet 52a for electronic component chips formed in the upper portion thereof. In the bottom end of the hopper 52, a discharge outlet 52b for discharging electronic component chips one by one is formed. A large number of electronic component chips supplied through the supplying inlet 52a at random is stored in the hopper 52. The hopper 52 is formed to be vibrated by connecting a vibrating source (not shown) thereto to thereby vibrate the hopper 52 so that electronic component chips are discharged one at a time from the discharge outlet 52b. 
On the other hand, a pipe 55 is connected to the discharge outlet 52b. The pipe 55 extends from the discharge outlet 52b of the hopper 52 toward the chute portion 54 side. The cross-section of the pipe 55 is to be in a shape suitable for transferring the one electronic component chip.
A sucking device (not shown) is connected to the topside of the pipe 55 to thereby transfer electronic component chips toward the top of the pipe 55 by sucking. The pipe 55 is formed of the buffer portion 53 and the chute portion 54. That is, the buffer portion 53 is equipped so as to align supplied electronic components to enable them to feed with constant timing. The pipe 55 has a length to some extent, so that plural electronic component chips supplied to the pipe 55 from the hopper 52 are transferred to the chute portion 54 side at constant spaces in a manner that electronic component chips in front of the pipe are pushed by electronic component chips in the rear during passing through the pipe 55. On the other hand, the chute portion 54 is formed of the top portion of the pipe 55, so that aligned electronic component chips are taken out one at a time from a top opening 55a of the pipe 55.
In the conventional electronic component chip feeder 51, numerous electronic component chips supplied into the hopper 52 at random are fed one at a time to the discharge outlet 52b colliding with one another in the hopper 52 by the applied vibration, as described above. Since the buffer portion 53 is formed of the pipe 55 having a length to some extent, front and rear electronic component chips collide with each other during passing through the pipe 55.
Accordingly, there has been a problem in which by friction between the electrodes formed on the outer surfaces of electronic component chips, the surface of a solder layer or a Sn layer formed on an electrode for promoting solderability is oxidized to be black so that solderability is reduced.
That is, as shown in FIG. 8, an electronic component 61 is soldered to electrodes 65 and 66 on a printed circuit board 64 utilizing the bottom surfaces of outer electrodes 62 and 63 of the electronic component 61. However, since the outer surfaces of the outer electrodes 62 and 63 are oxidized, solderability is prone to be reduced.
Recently, the size of an electronic component chip has been all the more reduced. Accordingly, the area of an electrode formed on the outer surface of an electronic component chip is becoming close to that of dust or shavings produced by collisions of the electronic component chips with one another. Therefore, when dust or shavings stick to the surfaces of electrodes, the reliability of electrical connections is prone to decrease due to reduced solderability.